Hi
Just looked at the wiring diagram there are two ignition coils, one for cylinders 1 and 3 and the other for 2 and 4 so if you were getting a spark on 4 you should I think be getting a spark on cylinder 2 as it’s the same coil ?
Also looking at the wiring diagram both ht leads for each coil needs to be connected to the plugs as each end of the secondary winding goes to a plug so if one plug is not connected or you have a bad connection or break down in the HT circuit you won’t get a spark or only a weak spark as then the HT “circuit” is compromised or broken
(On a single cylinder bike or a bike that has one coil per cylinder one side of the secondary winding goes to earth and the other goes to the plug and then earth so creating the circuit )
Also just for info the coils primary windings are one side connected to the points by a blue and yellow wire and the other side of the primary winding goes to the run switch and power to the coil is supplied by this black white wire from the run switch / ignition switch, and if any connection is corroded then like a bad supply from the ignition switch to the run switch or from this switch to the coil or if the the blue and yellow wires connections are bad voltage to the ignition system will be affected by this high resistance
(And as I have just rebuilt my CB400f front end with new switches and other new electrical parts can believe this, as it’s a right “snakes wedding” under the tank where the handlebar loom connects to the main loom
)
So if you suspect the ignition system supply is at fault if you connect via a temporary connection the black and white (that connection in the picture to the left of the points that looks like a “Y” direct to the battery “+” so you are bypassing the complete ignition switch so that the coils are constantly “live” and you get a good spark then you will wil then know it’s a fault with the ignition wiring but if you still have no spark the fault most likely is either with the points, coils, HT leads, plug cap or plugs
I am not a Honda expert but feel free to pm me and I will send you my number if you want some more help
Best wishes and stay safe Al
Sent from my iPhone using Tapatalk
